The storm that has plagued South Asia for many days has dissipated over land.

Millions of people across South Asia will be breathing a sigh of relief; Tropical Cyclone Roanu is no more. It finally broke up over northern Bangladesh, Myanmar, and the far southwest of China, losing its energy source: the warm waters of the Indian Ocean.

Roanu was the first cyclone of the Indian Ocean season that has two peaks: May-June and October-November; these peaks are in advance of the Southwesterly Monsoon and before the Northeasterly Monsoon, respectively.

Roanu began life as an area of low pressure to the southwest of Sri Lanka on May 14. By last Tuesday, 17 it had become a tropical cyclone and dropped up to 300mm across the island. The flooding and resulting landslides are known to have claimed the lives of 71 people with another 127 reported missing.

As Roanu then began to move northwards along the east coast of India, several locations reported rainfall of between 200mm-300mm.

Although Roanu was never a particularly powerful storm in terms of wind speeds - the maximum was 120km per hour, there were concerns about its impact on the northern end of the Bay of Bengal.

The high population density around the Ganges Delta, coupled with the fact that much of the region is less than five metres above sea level, makes it vulnerable to major cyclones.

Death tolls of between 300,000-500,000 have been recorded in the past during the worst storms. As recently as 1970, the Bhola cyclone claimed the lives of 300,000 people.

The shape of the Bay of Bengal funnels water, leading to storm surges. In fact, about 40 percent of the world's storm surges occur in the bay. Fortunately, this surge was no more than one metre high, but torrential rain and strong winds took their toll.

More than 20 people are known to have died. Although a tragedy for victims, the country seems to be improving its warning services and 500,000 people were evacuated before the storm hit.

Although Roanu is no longer a cyclone, it is still having an impact. There is still a cyclonic, or counterclockwise, circulation across the region. Heavy rain continues across northern Bangladesh and southwestern China. There is a risk of landslides in these areas.

The flow is also "sucking" in air from across northern India and Pakistan, where heatwave conditions have seen record-breaking temperatures well in excess of 50C. Consequently, the eastern states of India and Bangladesh can expect rising temperatures in the days to come.